Afraid of death and wondering if the afterlife is real - need guidance

Assalamualaikum, I'm not very old (an age you might guess but I can't say here) and I live in a Western country. Lately I feel distant from Allah and from my deen, and I've become really scared of death. I started praying namaz a bit late, around 11 or 12, and at first it felt comforting. After puberty (which wasn't long ago) I learned more about Islam and the world, but I also began drifting away. I fall into sins a lot - missing or rushing prayers, looking at inappropriate content, and talking about things I shouldn't. In the past few days I've been fixating on death and it's terrifying me. I worry about not existing or not being conscious anymore, and I think I'd be calmer if I had certainty that an afterlife exists and that Allah is real. I still consider myself Muslim and I believe in Islam and in Allah Subhanahu wa Ta'ala, but doubts about the truth of the message are creeping in. I pray this is not shaytaan trying to lead me off the straight path. I want to draw closer to Allah again and, inshaAllah, secure a place in Jannah for my family and myself. I also think I have some OCD tendencies that affect my worship. Sometimes I pray for half an hour or more and repeat parts of the prayer because I'm worried I did it wrong, or that Allah is displeased and something bad will happen if I don't repeat it. Another thing: my father grew up Muslim but became agnostic at a young age. He's not strictly atheist - he's philosophical and leans on science. I really want to help him return to Islam, because I feel this is the right path for him. How can I guide him without pushing him away? Can brothers and sisters share evidence or reminders that strengthen belief in Islam and the afterlife? Practical tips to get closer to Allah, sincere ways to repent, and gentle methods to help a parent find their way back would mean a lot. If there are resources or explanations about the afterlife and how it works, please share them too. JazakAllahu khairan for any advice and duas.